Unofficial Royal Enfield Community Forum
Royal Enfield Motorcycles => Bullet Iron Barrel => Topic started by: donkey on November 02, 2007, 08:48:13 am
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Hi guys!
I have my new Bullet since last friday. It's really amazing, I love it. But starting the bike it produces for too much time too much oiled white smoke. I think it's for excessive oil , but when I drain this to the correct oil level, the bike it's still produces de same oiled white smoke... I am a little worried...
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Donk,
Does this happen when you start the bike and then eventually stop? If so you are probably wet sumping. To stop this make sure the piston is at TDC on the compression stroke when you park the bike.
Keep the oil level around half way on the dip stick and make sure you screw the dip stick all the way down when you check the oil.
Where are you located?
--Leonard
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I'm from Spain.
Do you mean find TDC (0 on ampermeter) when stop and park the bike? or adjust TDC?
Thanks
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When stopping the bike, go through the start process without starting - get the ammeter to 0 again, and turn it off. I have had wet sumping one time, and it blows white smoke for a while, then runs completely clean.
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OK, so at the risk of being unpopular, would somebody who knows explain to me why TDC on the compression stroke prevents wet sumping; this makes no physical sense. The basic design, which I admire more every time I see something like this, seems to be such as to prevent wet sumping.
The top end is fed through the scavenge pump; drainback, if any, is going to be limited to the volume of oil in the lines and pump, and is going to have to seep past the pump block, etc; crankshaft position isn't going to matter there unless there's a crank position where all four holes in the pump are partly uncovered so drainback has a straight shot through the pump, which I don't believe is possible. If that were the case, then it's going to wet sump a lot and whether or not it's on the compression stroke won't matter. I'm guessing that when drainback does occur it's because oil seeps past the pump block for some reason, this is about the only mechanism. It's still only going to be about a teaspoon of oil or so; there's going to be that much floating around in the crankcase normally.
The bottom end is fed from the other end of the pump, through the quill thingie and crankshaft; the pump is below the level of the crankshaft, as is most of the volume of the oil tank, so there's no real hydraulic head. Oil would have to go uphill past the pump block to get to the crankcase.
So; the "stop at TDC" doesn't make sense; unlike a bike with an elevated oil tank, there's no mechanism for substantial amounts of oil to get to the crankcase. Doing it on the compression stroke makes it even more absurd; the oil system doesn't know where the valves are.
At a guess, when somebody gets the occasional mosquito-fog of smoke, a likely cause is oil past a valve guide; that'll go directly into the combustion chamber and even a tiny bit will smoke like a tire fire. It takes a lot of oil in the crankcase to get some sucked up into the combustion chamber, but not much at all past the valves to make a mess. A little before TDC on the compression stroke means both valves are closed is where the engine's going to stop anyway, but if for some reason there's a good bit of oil pooled in the head that hasn't drained back down the pushrod galley, it wouldn't be a stretch to have some seep past the guides and pool behind the valve. Result; a lot of smoke.
Anybody care to offer an explanation, other than, like deer whistles, it seems to work for them?
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Here's the explaination of wetsumping from Pete Snidal's book -
"In some conditions, since the level in the separate but integrally-cast oil tank is higher than the sump, oil may have migrated into the sump. For this reason, there is a separate sump drain at the bottom of the crankcase unit - the forward one; the rearward one is the drain for the tank itself. Wet-sumping is generally due to the machine having been left for a period of time with the crankshaft/flywheel assembly in a position in which the Big End journal crankpin is at the bottom. (ie, the piston is at, or close to, BDC - Bottom Dead Center.) This will sometimes allow oil to be siphoned from the tank through the one-way valving of the pressure-side oil pump and down into the big end, from where it will naturally leak through the clearance provided and accumulate in the crankcase."
My understanding is this is SOMETIMES a problem on SOME Bullets - I'm fairly haphazard on checking to see if my motor is close to TDC when I shut down - I sometimes check to see if I'm up to good compression, seems to be close enough. Bike seems to do it on its own, as everytime I've checked, the motor is right up to where I need the decomp to move the kickstart lever. I DO try to make a effort to check if the bike will be sitting for a while... like during a crisp fall in Michigan...
Mike and Stumpy in Michigan
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That makes sense; gravity drain from the tank, leaking past the pump block, thence through the crankshaft, and out the big end feed. If the crank throw is at or above the level of the oil in the tank, OR if the pump blocks are reasonably tight, no drainback can occur. If the pump blocks are sloppy AND the crank throw is at the bottom, then oil can seep through.
I'd expect the engine to stop partway into the compression cycle anyway, because of compression.
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But wet-sumping means the engine is burning excessive oil on startup and it produces blue smoke.
White smoke on startup is steam.
Tom
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If the oil level in the oil tank sump is at the top of the dipstick - and if the bike is smartly pushed off the center stand and stopped quickly by the brakes - a little bit of oil will splash over the internal baffle into the crankcase. And it will puff light blue smoke for a short time.
No different than start up after the bike has been jostling around in the back of a truck. Or hard stopping after coasting down a steep hill.
Regards, Foggy
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My bike usually wet sumps after sitting a week or two. You can drain the oil from the first drain plug on the bottom of engine if you wish and it won't smoke on start-up. Have had a lot of bikes , usually British or Sportster, do this. Maybe its a conspiracy to force us to keep the bearings and bushes deep inside the engine lubed.....Dew.
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When wetsumping, on my bike, the smoke is white.. There is no water anywhere in the bike, to produce steam. No doubt, if I got off the bike, and looked hard, I would see blue smoke, but against my environment it is white.
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Motorcycles will often blow steam out the exhaust if the muffler didn't get hot enough during the previous ride to burn off the accumulated condensation.
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White smoke....oil.......blue smoke.....to rich ;D.....Dew
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White smoke....oil.......blue smoke.....to rich ;D.....Dew
I never saw a two stroke motorcycle, scooter, moped, outboard motor or chainsaw blow white smoke! Nor an oil eating four stroke! ;)
Regards, Foggy
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Water is a by-product of combustion. In a cold engine it accumulates in the exhaust pipe and silencer and is boiled off as steam when the exhaust warms up. You often see a stream of water running from a car's exhaust-pipe in morning traffic-queues. Clouds of steam (white smoke) when a car starts on a cold day is not an unusual sight.
Engine burning oil = blue smoke.
Engine running very rich - black smoke.
Tom
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Well if my bike sits for a while it blows white smoke out the exhaust. If it is steam, it sure "smells" like burned motor oil. On bikes I've had in the past, that blue/black smoke was accompanied by a gasoline smell. I guess replacing those little jets in the carbs with smaller ones must have made the rings or valves seal in some mysterious manner which I don't understand because the blue/black smoke disappeared....Dew.